Multiple-mode dielectric resonators in which a dielectric core is disposed in a conductive cavity and in which a plurality of TE01 delta modes are subjected to multiplexing are known. In these dielectric resonators, such as those disclosed in the Patent Documents 1 and 2, a substantially cubic dielectric block is disposed in a substantially cubic cavity, and TE01 delta modes in which electric field vectors pass around three axes that are perpendicular to each other are subjected to triplexing.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-60804    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2001-60805
An example of a structure of a related multiple-mode dielectric resonator using a support base and examples of resonance modes that are set in the multiple-mode dielectric resonator are shown in FIGS. 17(A) and 17(B). In FIGS. 17(A) and 17(B), a support base 40 is formed of a dielectric member, and a dielectric core 1 is disposed in a central portion of a cavity 2 by supporting the dielectric core 1 in the cavity 2. In FIG. 17(A), electric field vectors of three TE01 delta modes (represented by a cylindrical coordinate system) are indicated by arrows. In FIG. 17(B), electric field vectors of three TM01 delta modes (represented by a cylindrical coordinate system) are similarly indicated by arrows.
However, in the related multiple-mode dielectric resonator, when an attempt is made to use the aforementioned three TE01 delta modes, the resonance modes of the three TM01 delta modes are set as spurious modes. The influences of the spurious modes (that is, the response of the spurious modes) give rise to the problem that proper attenuation characteristics cannot be obtained when the dielectric resonator is used as a filter.
To efficiently use the TE01 delta modes, it is necessary to secure the substantially cubic dielectric core so that it is raised. Accordingly, in the related art, as shown in FIGS. 17(A) and 17(B), the dielectric core 1 is adhered to the support base 40, formed of ceramic having a low dielectric constant, and the support base 40 is secured to the bottom surface in the cavity 2.
To adhere the dielectric core and the support base together with an adhesive, it is necessary to polish both the support base and the dielectric core and smooth an adhesion surface, resulting in increased costs. In addition, in general, long-term reliability of an adhesive is low. As a result, when the adhesive is placed in a high-temperature high-humidity environment for a long period of time and receives a strong impact, the dielectric core tends to separate from the support base.